SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5f7517da316fc19517152d7f25d5d391bf6eb0fc708b71548a9a3d9b9b906109' 
  AND token = 'B/jUVXhe+l2JGXYHZwH999ukEfG75MxZEs8ChSXZnvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}